IX totally has mechs! Ark counts, and even ignoring that you have a spaceship, cloning, and a likely cyborg.II, III, and IX are the only FF games that don't have mechs.
People seem to forget that.
Even then, those games have advanced airships like Ark, The Dreadnaught, and The Nautilus.
And even if it doesn't have mechs per se, III has ancient super civilizations that built a flying continent.
II may be the only one to downplay mechs and super technology, but that might depend on how you count Iron Giant, given that it debuts in that game as Warmech's replacement.